gcc/regs.h

   1 /* Define per-register tables for data flow info and register allocation.
   2    Copyright (C) 1987, 1993, 1994, 1995, 1997 Free Software Foundation, Inc.
   3
   4 This file is part of GNU CC.
   5
   6 GNU CC is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU CC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU CC; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21
  22
  23 #define REG_BYTES(R) mode_size[(int) GET_MODE (R)]
  24
  25 /* Get the number of consecutive hard regs required to hold the REG rtx R.
  26    When something may be an explicit hard reg, REG_SIZE is the only
  27    valid way to get this value.  You cannot get it from the regno.  */
  28
  29 #define REG_SIZE(R) \
  30   ((mode_size[(int) GET_MODE (R)] + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
  31
  32 #ifndef SMALL_REGISTER_CLASSES
  33 #define SMALL_REGISTER_CLASSES 0
  34 #endif
  35
  36 /* Maximum register number used in this function, plus one.  */
  37
  38 extern int max_regno;
  39
  40 /* Maximum number of SCRATCH rtx's in each block of this function.  */
  41
  42 extern int max_scratch;
  43
  44 /* Register information indexed by register number */
  45 typedef struct reg_info_def {
  46                                 /* fields set by reg_scan */
  47   int first_uid;                /* UID of first insn to use (REG n) */
  48   int last_uid;                 /* UID of last insn to use (REG n) */
  49   int last_note_uid;            /* UID of last note to use (REG n) */
  50
  51                                 /* fields set by both reg_scan and flow_analysis */
  52   int sets;                     /* # of times (REG n) is set */
  53
  54                                 /* fields set by flow_analysis */
  55   int refs;                     /* # of times (REG n) is used or set */
  56   int deaths;                   /* # of times (REG n) dies */
  57   int live_length;              /* # of instructions (REG n) is live */
  58   int calls_crossed;            /* # of calls (REG n) is live across */
  59   int basic_block;              /* # of basic blocks (REG n) is used in */
  60   char changes_size;            /* whether (SUBREG (REG n)) changes size */
  61 } reg_info;
  62
  63 extern reg_info *reg_n_info;
  64
  65 extern unsigned int reg_n_max;
  66
  67 /* Check for REG_N_xxx macros being in bound, return N for use as an
  68    index.  */
  69 #ifdef ENABLE_CHECKING
  70 #define REG_N_CHECK(N)                                                  \
  71 ((((unsigned)(N) < (unsigned)reg_n_max)                                 \
  72  ? 0 : (fatal ("Register %d out of bounds", (N)), 0)), (N))
  73 #else
  74 #define REG_N_CHECK(N) (N)
  75 #endif
  76
  77 /* Indexed by n, gives number of times (REG n) is used or set.
  78    References within loops may be counted more times.  */
  79
  80 #define REG_N_REFS(N) (reg_n_info[REG_N_CHECK (N)].refs)
  81
  82 /* Indexed by n, gives number of times (REG n) is set.
  83    ??? both regscan and flow allocate space for this.  We should settle
  84    on just copy.  */
  85
  86 #define REG_N_SETS(N) (reg_n_info[REG_N_CHECK (N)].sets)
  87
  88 /* Indexed by N, gives number of insns in which register N dies.
  89    Note that if register N is live around loops, it can die
  90    in transitions between basic blocks, and that is not counted here.
  91    So this is only a reliable indicator of how many regions of life there are
  92    for registers that are contained in one basic block.  */
  93
  94 #define REG_N_DEATHS(N) (reg_n_info[REG_N_CHECK (N)].deaths)
  95
  96 /* Indexed by N; says whether a pseudo register N was ever used
  97    within a SUBREG that changes the size of the reg.  Some machines prohibit
  98    such objects to be in certain (usually floating-point) registers.  */
  99
 100 #define REG_CHANGES_SIZE(N) (reg_n_info[REG_N_CHECK (N)].changes_size)
 101
 102 /* Get the number of consecutive words required to hold pseudo-reg N.  */
 103
 104 #define PSEUDO_REGNO_SIZE(N) \
 105   ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)         \
 106    / UNITS_PER_WORD)
 107
 108 /* Get the number of bytes required to hold pseudo-reg N.  */
 109
 110 #define PSEUDO_REGNO_BYTES(N) \
 111   GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
 112
 113 /* Get the machine mode of pseudo-reg N.  */
 114
 115 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
 116
 117 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */
 118
 119 #define REG_N_CALLS_CROSSED(N) (reg_n_info[REG_N_CHECK (N)].calls_crossed)
 120
 121 /* Total number of instructions at which (REG n) is live.
 122    The larger this is, the less priority (REG n) gets for
 123    allocation in a hard register (in global-alloc).
 124    This is set in flow.c and remains valid for the rest of the compilation
 125    of the function; it is used to control register allocation.
 126
 127    local-alloc.c may alter this number to change the priority.
 128
 129    Negative values are special.
 130    -1 is used to mark a pseudo reg which has a constant or memory equivalent
 131    and is used infrequently enough that it should not get a hard register.
 132    -2 is used to mark a pseudo reg for a parameter, when a frame pointer
 133    is not required.  global.c makes an allocno for this but does
 134    not try to assign a hard register to it.  */
 135
 136 #define REG_LIVE_LENGTH(N) (reg_n_info[REG_N_CHECK (N)].live_length)
 137
 138 /* Vector of substitutions of register numbers,
 139    used to map pseudo regs into hardware regs.
 140
 141    This can't be folded into reg_n_info without changing all of the
 142    machine dependent directories, since the reload functions
 143    in the machine dependent files access it.  */
 144
 145 extern short *reg_renumber;
 146
 147 /* Vector indexed by hardware reg
 148    saying whether that reg is ever used.  */
 149
 150 extern char regs_ever_live[FIRST_PSEUDO_REGISTER];
 151
 152 /* Vector indexed by hardware reg giving its name.  */
 153
 154 extern char *reg_names[FIRST_PSEUDO_REGISTER];
 155
 156 /* For each hard register, the widest mode object that it can contain.
 157    This will be a MODE_INT mode if the register can hold integers.  Otherwise
 158    it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
 159    register.  */
 160
 161 extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
 162
 163 /* Vector indexed by regno; gives uid of first insn using that reg.
 164    This is computed by reg_scan for use by cse and loop.
 165    It is sometimes adjusted for subsequent changes during loop,
 166    but not adjusted by cse even if cse invalidates it.  */
 167
 168 #define REGNO_FIRST_UID(N) (reg_n_info[REG_N_CHECK (N)].first_uid)
 169
 170 /* Vector indexed by regno; gives uid of last insn using that reg.
 171    This is computed by reg_scan for use by cse and loop.
 172    It is sometimes adjusted for subsequent changes during loop,
 173    but not adjusted by cse even if cse invalidates it.
 174    This is harmless since cse won't scan through a loop end.  */
 175
 176 #define REGNO_LAST_UID(N) (reg_n_info[REG_N_CHECK (N)].last_uid)
 177
 178 /* Similar, but includes insns that mention the reg in their notes.  */
 179
 180 #define REGNO_LAST_NOTE_UID(N) (reg_n_info[REG_N_CHECK (N)].last_note_uid)
 181
 182 /* This is reset to LAST_VIRTUAL_REGISTER + 1 at the start of each function.
 183    After rtl generation, it is 1 plus the largest register number used.  */
 184
 185 extern int reg_rtx_no;
 186
 187 /* Vector indexed by regno; contains 1 for a register is considered a pointer.
 188    Reloading, etc. will use a pointer register rather than a non-pointer
 189    as the base register in an address, when there is a choice of two regs.  */
 190
 191 extern char *regno_pointer_flag;
 192 #define REGNO_POINTER_FLAG(REGNO) regno_pointer_flag[REGNO]
 193 extern int regno_pointer_flag_length;
 194
 195 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
 196    that have to go in the same hard reg.  */
 197 extern rtx regs_may_share;
 198
 199 /* Vector mapping pseudo regno into the REG rtx for that register.
 200    This is computed by reg_scan.  */
 201
 202 extern rtx *regno_reg_rtx;
 203
 204 /* Flag set by local-alloc or global-alloc if they decide to allocate
 205    something in a call-clobbered register.  */
 206
 207 extern int caller_save_needed;
 208
 209 /* Predicate to decide whether to give a hard reg to a pseudo which
 210    is referenced REFS times and would need to be saved and restored
 211    around a call CALLS times.  */
 212
 213 #ifndef CALLER_SAVE_PROFITABLE
 214 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 215 #endif
 216
 217 /* On most machines a register class is likely to be spilled if it
 218    only has one register.  */
 219 #ifndef CLASS_LIKELY_SPILLED_P
 220 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
 221 #endif
 222
 223 /* Allocated in local_alloc.  */
 224
 225 /* A list of SCRATCH rtl allocated by local-alloc.  */
 226 extern rtx *scratch_list;
 227 /* The basic block in which each SCRATCH is used.  */
 228 extern int *scratch_block;
 229 /* The length of the arrays pointed to by scratch_block and scratch_list.  */
 230 extern int scratch_list_length;
 231
 232 /* Allocate reg_n_info tables */
 233 extern void allocate_reg_info PROTO((int, int, int));